How viable Spearazons are in HC really depends on two things- whether you go physical or lightning, and just how good of a player you are. I have friends who refer to Spearazons as "suicide on a stick". I've known people who made guardian with one... but I also knew someone who made guardian without assigning a single skill point whatsoever. If you're good enough, you can make guardian with almost anything.
I would strongly recommend against a Spearazon as your 1st hardcore character. If it's your 20th, and you already have a dozen guardians, then feel free to give it a try, but understand that it'll be the toughest thing you've ever tried. It ranks way up there with meleemancers in terms of "builds you'd have to be crazy to try". Jabazons, Impaleazons, and Fendazons all suffer from all sorts of bugs, challenges, problems, etc.
Lightning Spearazons are much, much easier than physical spearazons, but they're still tough. It helps that you can pump D/A/E to your heart's content. It also helps that you have a substantial source of damage that's entirely weapon-independent (LS or CS), as well as very strong physical support (Jab or Valk)- plus you've got a nice handy built-in IM solution. Lightning Strike is bugged, and is the more difficult skill to use properly (monster spacing is everything- too far apart or too close together and your Lightning will sizzle before it arcs to its full potential, and the NextDelay means you're better off swinging once and waiting than you are constantly swinging), but even that's viable. I've personally taken a Lightning Spearazon through Hell. It was softcore, but I had no deaths, so I know it's viable. Difficult, but hardly suicidal like Fendazons. With proper Valk and Decoy usage, I'd probably rank it on par with a Tesladin or a Frenzy Barb in terms of difficulty.